Posted in News & Press     |     Oct 16th 2018

Using a Gravimetric Analyser to Study Water’s Microscopic Mobility in Polymer Membranes

Quantifying the rate of moisture and vapor transport through polymeric packaging media with gravimetric analysers is of critical importance for a multiplicity of industrial and commercial fields. It most broadly affects the food and beverage industry and the pharmaceutical sector, where products may be subject to phase and stability changes due to chemical variations.

Dosage form tablets, for example, may succumb to amorphic phase changes when permeated by microscopic levels of water. This can significantly impact their efficacy and shelf life. Polymeric packaging is designed to resist permeation by moisture and vapor to maximise the longevity of moisture-sensitive products and ensure they meet the necessary regulatory standards for distinct sectors.

This blog post will outline a study that aimed to determine water content isotherms with diffusion measurements to characterise changes in water mobility behaviour of polymer films at high water concentrations.

Testing Concentration Dependent Mobility of Water with a Gravimetric Analyser

This study used an IGAsorp gravimetric analyser to determine the isothermal concentration of water vapour and the chemical diffusion coefficient of two polymer films – treated and untreated. The isothermal concentration of water vapour refers to changes in water concentration within the polymer film as a function of temperature. The chemical diffusion coefficient is based on Fick’s law of diffusion and was calculated as a measure of temperature and concentration dependent on the sample’s distinct properties.

Each of these metrics was used to determine the transmission rates of water through polymer membranes of varying thicknesses. They were used in tandem to provide a detailed assessment of how microscopic water mobility changes in relation to concentration, providing novel data regarding relative changes in mobility as a function of concentration.

It showed that the untreated polymer achieved a water content of almost 35% higher compared to the treated sample. There were significant differences between the polymers in the diffusive behaviour until higher humidity (>70%) where the trends were similar.

Gravimetric Analysers from Hiden Isochema

Hiden Isochema is one of the world’s leading manufacturers of dynamic vapour sorption analysers and gravimetric sorption analysers. The IGAsorp DVS analysers are used in hundreds of R&D and process laboratories and are equally popular in both academic and industrial sectors. Key areas include: pharmaceutical, biotech, polymers and packaging, natural materials, building and construction materials (cement, timber, insulation, adhesives), electronics and fuel cells (proton exchange membranes).

If you would like to learn more about this study, read our full technical note: concentration dependence of the microscopic mobility of water in polymer membranes. Or, contact us for any more details about the IGAsorp gravimetric analyser.

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